A single-flask synthesis of α-alkylidene and α-benzylidene lactones from ethoxyacetylene, epoxides/oxetanes, and carbonyl compounds
作者:Kevin Ng、Vincent Tran、Thomas Minehan
DOI:10.1016/j.tetlet.2015.12.041
日期:2016.1
α-alkylidene and α-benzylidene lactones (5) in good to excellent yields. This one-pot process, in which three new carbon–carbon bonds and a ring are formed, affords substituted α,β-unsaturated lactones of predominantly Z-configuration. The reaction likely occurs via alkyne–carbonyl metathesis of a hydroxy–ynol ether intermediate, acid-promoted alkene E- to Z-isomerization, and lactonization.
在BF 3 ·OEt 2存在下用环氧化物或氧杂环丁烷进行低温处理(乙氧基乙炔基)锂,然后添加醛或酮并升温至室温,得到结构上不同的五元和六元α-亚烷基和α-亚苄基内酯(5)的产率高至优异。这个一锅法,其中形成三个新的碳-碳键和一个环,可得到取代的α,β-不饱和内酯,主要为Z-构型。该反应可能是通过羟基-炔醇醚中间体的炔烃-羰基复分解,酸促进的烯烃E-到Z-异构化和内酯化而发生的。